You do not have a violation of the Anti-deficiency Act. What you have is a person who is not a contracting officer directing a contractor to do $24k worth of work. Only a Contracting Officer can bind the government. What will have to be decided is whether the person who told the contractor to do the work will have to pay for the work or whether it will be ratified and the VA pays for the work.
Let's say the Contracting Officer had $20k of certified funds on the contract, but the contract was awarded for $24k. As long as you had the funds available for facilities maintenance you would not be anti-deficient. The keys is having funds available at the time of the action. In the example I just provided a mod would need to be written adding $4k of additional funds to the contract. In this example I am only explaining how it would not be an ADA violation, I am not saying this is how it should be done. The correct way is to originally have all $24K on the contract.